The US government, which was outraged by Scotland's decision to free the former Libyan airline security chief, said his death concluded "an unfortunate chapter."

"We will continue working with our new partners in Libya toward a full accounting of (Muammar) Gaddafi's horrific acts," said US National Security Council spokesman Tommy Vietor.

Libya's interim government pledged its full co-operation with any further inquiries into the Lockerbie bombing, which some, particularly in Britain, have blamed on Iran and its Palestinian allies rather than Gaddafi.

"In Libya, it is in our interest to close this case and bring out the truth," said Transitional National Council spokesman Mohammed Harizi. "We want to expose the crimes of Gaddafi which did so much harm to the Libyan people."

Britain's Independent newspaper demanded a public inquiry but its calls were rejected by Prime Minister David Cameron who again criticised Megrahi's release by the Scottish authorities, who have devolved powers in judicial affairs.

"Megrahi's death is no reason to stop trying to get to the truth," said the newspaper's editorial.

Cameron insisted: "There was a proper process, a proper court proceeding and all the rest of it. We have to give people the chance to mourn those that were lost."

The fact that Megrahi survived much longer than the doctors had estimated provoked indignation in Britain and the United States.

The convict had been greeted as a hero on his return to Gaddafi's Libya, after having served eight years of a minimum 27-year sentence for his role in the Lockerbie bombing.

Several relatives of US citizens killed in the Lockerbie bombing said they were pleased that Megrahi had died.

"He deserved to die," said Susan Cohen, whose daughter Theodora was one of the victims.

"He was a mass murderer. I feel no pity around him. He got to die with his family around him. My daughter, at age 20, died a brutal, horrible death," she told CNN.

But the British father of one of the victims, who has long believed Megrahi was innocent, said it was a sad day.

"It is a sad time, I think. I have been satisfied for some years that this man was nothing to do with the murder of my daughter," Jim Swire, whose daughter Flora was killed in the attack, told the BBC,

"I think Scotland has a big question to answer as to why his verdict hasn't long since been reviewed."

In December, Megrahi told several British newspapers in what was billed as a "final interview" that a book being written by investigative journalist John Ashton would clear his name.